Is NAC better than glutathione?

For most people, yes. NAC scores 8.0 against glutathione's 6.2, costs $5 to $15 a month against $20 to $45, and wins the liver, respiratory, antioxidant and mood rows. Glutathione takes one row, immune function, on the strength of Richie 2015, where 1,000 mg a day for 6 months raised body stores 30 to 35 percent and more than doubled natural-killer cytotoxicity.

Does oral glutathione actually get absorbed?

Plain oral capsules mostly do not. Witschi 1992 gave 7 people a single dose of about 3 g and saw no rise in plasma glutathione over 270 minutes, and Schmitt 2015 found plain oral failed to move the reduced-to-oxidized ratio where the sublingual form succeeded (p=0.002). Chronic dosing is the exception. Richie 2015 ran 1,000 mg a day for 6 months and did raise body stores by 30 to 35 percent, so the route works on a timescale of months rather than hours.

Can I take NAC and glutathione together?

You can, but you are paying twice to fill the same pool. NAC supplies the rate-limiting cysteine the body uses to build glutathione, so the two end at the same place. If you want a combination with human data behind it, Kumar 2023 tested glycine plus NAC in 24 older adults over 16 weeks and corrected glutathione deficiency along with oxidative stress and physical function.

Which one is cheaper?

NAC, by roughly three times. It runs $5 to $15 a month for 600 to 1,200 mg a day, and that figure is extracted from the source report rather than estimated. Glutathione runs $20 to $45 a month at 1,000 mg a day, an estimate priced 2026-09-07 covering plain oral bottles at $20 to $30 per 60 capsules and liposomal Setria products at $32 to $45.

How long before I know whether either one is working?

Both carry a 12-week assessment window, so judge at 12 weeks either way. NAC gives a first noticeable change at about 2 weeks and reaches full effect at around 12 months. Glutathione registers at about 4 weeks with full effect at about 6 months, and those two figures are estimated rather than extracted, so hold them loosely.

Is IV glutathione worth it?

The evidence says no, and the risk sits there rather than in the capsule. Aebi 1991 found IV glutathione raised plasma total glutathione to 823 micromol per litre with a 14.1 minute half-life, so the spike clears almost immediately. Hauser 2009 randomized 21 Parkinson patients to IV glutathione and beat placebo by only 2.8 UPDRS units (p=0.32). Philippine FDA Advisory 2019-182 warns against unapproved injectable glutathione, citing organ toxicity and Stevens-Johnson syndrome.

Will NAC protect my kidneys before a contrast scan?

No. This is the clearest settled-negative result in either citation record. ACT 2011 randomized 2,308 patients and found contrast-induced nephropathy at 12.7 percent in both arms, and PRESERVE 2018 randomized 4,993 and found the composite at 4.6 against 4.5 percent (OR 1.02, p=0.88). Glutathione was never tested for this at all.

Who should avoid these?

Both reports list pregnancy and breastfeeding without medical supervision as contraindications, so start there. NAC adds nitrates because of additive hypotension, active peptic ulcer disease, anticoagulant or antiplatelet therapy, cysteine hypersensitivity, and reactive airway disease for the inhaled mucolytic form only. Glutathione adds sulfur or sulfite sensitivity, plus asthma for the inhaled and nebulized forms.

Head-to-Head Comparison

NAC vs Glutathione: Which Is Better for Your Liver?

Should I take NAC or glutathione?

Reviewed 09/07/2026

NAC scores 8.0 and glutathione 6.2, and that gap is real. NAC is the cheaper upstream precursor with a six-decade clinical record, so start there. Glutathione earns its place only when you want the finished molecule for immune markers, and only through a route that absorbs, which plain oral capsules often do not.

NAC 8.0, glutathione 6.2. This is one of the few pairs where the overall scores and the trial record agree.
NAC is the precursor, glutathione is the product. Supplying the rate-limiting cysteine is the cheaper way to raise the same pool.
Plain oral glutathione is the weak link. A single 3 g dose did not raise plasma glutathione at all in Witschi 1992.
Glutathione still wins one row. Richie 2015 raised body stores 30 to 35 percent over 6 months and more than doubled natural-killer cytotoxicity.
NAC runs $5 to $15 a month against $20 to $45 for glutathione, and the NAC figure is extracted from the source report rather than estimated.
Two NAC headlines are settled negative. Contrast-induced nephropathy failed in ACT and PRESERVE, and pulmonary fibrosis monotherapy was null.

At a Glance

Option B

Glutathione (GSH)

6.2 / 10 Worth trying

Upside

Efficacy 2.6
Breadth 3.0
Evidence 2.8
Speed 2.5
Durability 2.3
Bioindividuality 3.0

Downside

Safety Risk 1.6
Side Effects 1.7
Cost 2.2
Effort 2.0
Opportunity Cost 2.4
Dependency 1.3
Reversibility 1.3

Best at:

Antioxidant 6.5
Liver Detox 6.0
Immune Function 5.5
Metabolic Health 5.2

The finished tripeptide itself, taken orally. BioHarmony 6.2, worth trying.

Read full BioHarmony report →

Head-to-Head Verdict

Use Case	Winner	Rationale
Liver Detox	NAC (N-Acetylcysteine)	NAC subrating 8.0 against glutathione's 6.0, and this is the row with the strongest outcome data in the whole comparison. Smilkstein 1988 (n=2,540) cut hepatotoxicity to 6.1 percent when NAC started within 10 hours against 26.4 percent at 10 to 24 hours. Glutathione's liver evidence is Honda 2017, an open-label pilot in 34 people that lowered ALT from 68.9 to 58.1 IU/L.
Respiratory	NAC (N-Acetylcysteine)	NAC 7.5 against 3.5, the widest gap in the matrix. Zheng 2014 (PANTHEON, n=1,006) cut COPD exacerbations from 1.49 to 1.16 per patient-year at 600 mg twice daily, and Poole 2019 pooled 38 trials and 10,377 patients with a number needed to treat of about 8. Dose matters: 600 mg once daily was null in BRONCUS. Glutathione has no respiratory outcome trial.
Antioxidant	NAC (N-Acetylcysteine)	NAC 7.5 against 6.5, and the reason is absorption rather than potency. Schmitt 2015 ran NAC, plain oral glutathione and sublingual glutathione in the same crossover subjects, and plain oral glutathione failed to move the reduced-to-oxidized ratio while the sublingual form did. Allen 2011 gave 500 mg twice daily for 4 weeks and found no change in oxidative-stress markers.
Immune Function	Glutathione (GSH)	Glutathione 5.5 against NAC's 5.0, and the lower-scoring intervention wins this row on evidence. Richie 2015 was a 6-month double-blind RCT in 54 people where 1,000 mg a day raised body stores 30 to 35 percent and more than doubled natural-killer cytotoxicity. NAC has no comparable immune endpoint in its citation record.
Mood	NAC (N-Acetylcysteine)	NAC 6.0 against 2.5, though the evidence contradicts itself. Berk 2008 found a MADRS mean difference of -8.05 in bipolar depression and Fernandes 2016 pooled 5 trials with an SMD of 0.37. Berk 2019 then ran 181 people and found nothing at 16 weeks. Glutathione has no psychiatric trial at all, so NAC wins a row it has not fully earned.
Fertility Male	NAC (N-Acetylcysteine)	NAC 4.0 against 3.0. Ciftci 2009 gave 600 mg a day for 3 months to 120 men with idiopathic infertility and improved volume, motility and viscosity, with no change in concentration or morphology. That is a partial result on one endpoint set, and it is still more than glutathione has here.
Metabolic Health	Tie	Glutathione's subrating is 5.2 against NAC's 4.0, and neither number rests on a metabolic outcome trial. The closest thing in either citation record is Kumar 2023, a 16-week trial of glycine plus NAC in 24 older adults, which tests the precursor combination rather than glutathione itself. Call this even and pick on price.
Kidney Function	Tie	NAC 3.0 against 2.5, and the honest answer is that neither belongs here. NAC's kidney question was settled negative twice: ACT 2011 found contrast- induced nephropathy at 12.7 percent in both arms across 2,308 patients, and PRESERVE 2018 found 4.6 against 4.5 percent in 4,993. Glutathione has no renal trial in either direction.
Heavy Metal Detox	Tie	Both score 3.0, and neither citation record contains a chelation or metal-excretion trial. Glutathione powers Phase II conjugation through glutathione-S-transferase, which is the mechanism people point at, but a pathway is not an outcome. Nothing in this comparison supports either compound as a heavy-metal protocol.

Cost Comparison

Intervention	Monthly Cost	Notes
NAC	$5 to $15	Extracted from the source report rather than estimated, priced 2026-09-07, retail channel. The report prices NAC at $5 to $15 a month for 600 to 1,800 mg a day of retail capsules, and the 600 to 1,200 mg protocol sits in the low half of that band. This is one of the cheapest evidenced supplements you can buy.
Glutathione	$20 to $45	ESTIMATE, priced 2026-09-07, retail channel. At 1,000 mg a day the protocol needs 60 capsules of 500 mg a month. Plain oral bottles run about $20 to $30 per 60 capsules and liposomal Setria products $32 to $45. The provenance on this figure is estimated, so treat the band as a planning number rather than a measured price.
The difference	$15 to $30 a month, roughly three times the price	At the recommended doses on both reports you are comparing $5 to $15 against $20 to $45. Over a year that is $60 to $180 against $240 to $540.The price gap matters more than usual here because the two are aimed at the same glutathione pool. Paying triple for the finished molecule only makes sense when you have a reason the precursor route will not work for you.

When to Switch

Both sides share a 12-week assessment window, so the judging date is the same whichever you start with. NAC gives a first noticeable change at about 2 weeks and reaches full effect at around 12 months. Glutathione takes about 4 weeks to register and reaches full effect at about 6 months, and its provenance on those numbers is estimated rather than extracted, so hold them loosely.

Move from glutathione to NAC when cost matters, when your target is the liver or the airways, or when you are taking plain oral capsules and have no marker showing they did anything. That last case is the common one, because Witschi 1992 found a single 3 g oral dose did not raise plasma glutathione at all. Move the other way, from NAC to glutathione, for one reason: you want the immune endpoint Richie 2015 measured, you will run 1,000 mg a day for 6 months, and you will use a sublingual or liposomal route rather than a plain capsule.

Running both at once is the option to think hardest about, because you are paying twice to fill the same pool. If you want to combine anything, the combination with human data behind it is glycine plus NAC, which is what Kumar 2023 tested.

Who Should Pick What?

You want one cheap antioxidant and have no specific target

NAC (N-Acetylcysteine)

$5 to $15 a month against $20 to $45, a higher score on 12 of the 18 shared use cases, and a six-decade safety record. When nothing about your situation points at the finished molecule, buy the precursor.

You have COPD or chronic bronchitis with thick secretions

NAC (N-Acetylcysteine)

Respiratory subrating 7.5 against 3.5. Zheng 2014 used 600 mg twice daily and cut exacerbations by roughly a fifth, and Poole 2019 pooled 10,377 patients. Take the twice-daily dose, because 600 mg once daily was null in BRONCUS. Glutathione has nothing here.

You want to raise measured glutathione stores and track an immune marker

Glutathione (GSH)

Richie 2015 is the trial that did exactly this: 1,000 mg a day for 6 months, stores up 30 to 35 percent, natural-killer cytotoxicity more than doubled. Commit to the full 6 months and a route that absorbs, or the money is wasted.

You are exploring an adjunct for OCD, hair-pulling or addiction relapse

NAC (N-Acetylcysteine)

Mood subrating 6.0 against 2.5, and glutathione has no psychiatric data. Read the NAC evidence honestly though: Grant 2009 found 56 percent much or very much improved against 16 percent on placebo, and Bloch 2013 found nothing in children. Adjunctive and clinician-supervised only.

You are taking plain oral glutathione capsules right now

NAC (N-Acetylcysteine)

This is the route with the worst evidence in the comparison. Witschi 1992 found a single 3 g dose did not move plasma glutathione, and Schmitt 2015 found plain oral failed to shift the reduced-to-oxidized ratio where sublingual worked. Switch the route or switch the compound.

You are hoping to prevent contrast-induced kidney injury before a scan

Tie

Neither. ACT 2011 found identical 12.7 percent rates across 2,308 patients and PRESERVE 2018 found 4.6 against 4.5 percent across 4,993. That question is closed. Glutathione was never tested for it. Ask your clinician about hydration protocols instead.

You are pregnant, breastfeeding, or on anticoagulants

Tie

Neither without medical supervision. Both reports list pregnancy and lactation as contraindications. NAC adds nitrates, active peptic ulcer disease, anticoagulant or antiplatelet therapy, and cysteine hypersensitivity. Glutathione adds sulfur or sulfite sensitivity.

Research Highlights

Mechanism Difference
These two are redundant, not complementary, and the redundancy runs in one direction. NAC supplies the rate-limiting cysteine the body needs to build glutathione, so it raises the same pool that oral glutathione is sold to raise. Both end at the same endpoint.NAC also does three things glutathione does not: it acts as a direct sulfhydryl antioxidant, it breaks mucin disulfide bonds, and it modulates glutamate through the cystine-glutamate antiporter. Glutathione's own pathways, glutathione peroxidase and Phase II conjugation, run downstream of the pool NAC fills.
Safety Comparison
Both are benign by mouth. NAC scores 1.6 on safety risk and 1.8 on side effects, glutathione 1.6 and 1.7. Oral NAC causes mild GI upset and a sulfur smell across a six-decade record. Pakravan 2013 established that the anaphylactoid reactions people worry about are non-IgE histamine reactions that happen early in hospital IV infusion, not with oral use.Glutathione's risk lives entirely in one channel. Philippine FDA Advisory 2019-182 warns against unapproved injectable glutathione for skin lightening, citing liver, kidney and nervous-system toxicity and Stevens-Johnson syndrome. That is a sourcing problem rather than a property of the molecule.
Cost Comparison
NAC runs $5 to $15 a month for 600 to 1,200 mg a day, a figure extracted from the source report rather than estimated. Glutathione runs $20 to $45 a month at 1,000 mg a day, and that band is an estimate priced 2026-09-07, covering plain oral bottles at $20 to $30 per 60 capsules and liposomal Setria products at $32 to $45.Roughly three times the price for the finished molecule. Since both are aimed at the same glutathione pool, the premium only makes sense when you have a specific reason the precursor route will not serve you.
Editorial Verdict
Take NAC. It scores 8.0 against 6.2, costs a third as much, and carries the only life-saving outcome in either citation record. Smilkstein 1988 (n=2,540) and Prescott 1979 (n=100) built the acetaminophen-overdose antidote, and Zheng 2014 (n=1,006) built the COPD case.Glutathione has one row worth paying for: Richie 2015 raised body stores 30 to 35 percent and more than doubled natural-killer cytotoxicity over 6 months at 1,000 mg a day. Schmitt 2015 is the only direct comparison of the two, and it tested absorption rather than a clinical outcome.
Durability
Neither compound leaves a lasting mark once you stop. NAC's durability dimension scores 3.5 and glutathione's 2.3, and both work by keeping a pool topped up rather than changing what the body does on its own.The onset numbers say the same thing from the other end. NAC registers at about 2 weeks and keeps improving out to 12 months. Glutathione registers at about 4 weeks with full effect at 6 months, on estimated rather than extracted provenance. Richie 2015 needed the full 6 months of daily dosing to move stores at all.

Frequently Asked Questions

Is NAC better than glutathione?: For most people, yes. NAC scores 8.0 against glutathione's 6.2, costs $5 to $15 a month against $20 to $45, and wins the liver, respiratory, antioxidant and mood rows. Glutathione takes one row, immune function, on the strength of Richie 2015, where 1,000 mg a day for 6 months raised body stores 30 to 35 percent and more than doubled natural-killer cytotoxicity.
Does oral glutathione actually get absorbed?: Plain oral capsules mostly do not. Witschi 1992 gave 7 people a single dose of about 3 g and saw no rise in plasma glutathione over 270 minutes, and Schmitt 2015 found plain oral failed to move the reduced-to-oxidized ratio where the sublingual form succeeded (p=0.002).Chronic dosing is the exception. Richie 2015 ran 1,000 mg a day for 6 months and did raise body stores by 30 to 35 percent, so the route works on a timescale of months rather than hours.
Can I take NAC and glutathione together?: You can, but you are paying twice to fill the same pool. NAC supplies the rate-limiting cysteine the body uses to build glutathione, so the two end at the same place. If you want a combination with human data behind it, Kumar 2023 tested glycine plus NAC in 24 older adults over 16 weeks and corrected glutathione deficiency along with oxidative stress and physical function.
Which one is cheaper?: NAC, by roughly three times. It runs $5 to $15 a month for 600 to 1,200 mg a day, and that figure is extracted from the source report rather than estimated. Glutathione runs $20 to $45 a month at 1,000 mg a day, an estimate priced 2026-09-07 covering plain oral bottles at $20 to $30 per 60 capsules and liposomal Setria products at $32 to $45.
How long before I know whether either one is working?: Both carry a 12-week assessment window, so judge at 12 weeks either way. NAC gives a first noticeable change at about 2 weeks and reaches full effect at around 12 months. Glutathione registers at about 4 weeks with full effect at about 6 months, and those two figures are estimated rather than extracted, so hold them loosely.
Is IV glutathione worth it?: The evidence says no, and the risk sits there rather than in the capsule. Aebi 1991 found IV glutathione raised plasma total glutathione to 823 micromol per litre with a 14.1 minute half-life, so the spike clears almost immediately.Hauser 2009 randomized 21 Parkinson patients to IV glutathione and beat placebo by only 2.8 UPDRS units (p=0.32). Philippine FDA Advisory 2019-182 warns against unapproved injectable glutathione, citing organ toxicity and Stevens-Johnson syndrome.
Will NAC protect my kidneys before a contrast scan?: No. This is the clearest settled-negative result in either citation record. ACT 2011 randomized 2,308 patients and found contrast-induced nephropathy at 12.7 percent in both arms, and PRESERVE 2018 randomized 4,993 and found the composite at 4.6 against 4.5 percent (OR 1.02, p=0.88). Glutathione was never tested for this at all.
Who should avoid these?: Both reports list pregnancy and breastfeeding without medical supervision as contraindications, so start there.NAC adds nitrates because of additive hypotension, active peptic ulcer disease, anticoagulant or antiplatelet therapy, cysteine hypersensitivity, and reactive airway disease for the inhaled mucolytic form only. Glutathione adds sulfur or sulfite sensitivity, plus asthma for the inhaled and nebulized forms.

Evidence Sources

Observational Efficacy of oral N-acetylcysteine in the treatment of acetaminophen overdose (1988) n=2,540. Hepatotoxicity 6.1 percent when NAC started within 10 hours against 26.4 percent at 10 to 24 hours.
RCT Twice-daily N-acetylcysteine 600 mg for exacerbations of COPD (PANTHEON) (2014) n=1,006. Exacerbations 1.16 against 1.49 per patient-year, RR 0.78 (95% CI 0.67 to 0.90).
RCT Effects of N-acetylcysteine on outcomes in COPD (BRONCUS) (2005) n=523 at 600 mg once daily. Null for FEV1 decline and exacerbations, which is what makes the benefit dose-dependent.
Systematic review Mucolytic agents versus placebo for chronic bronchitis or COPD, Cochrane (2019) 38 trials, 10,377 patients. Peto OR 1.73 for staying exacerbation-free, number needed to treat about 8.
RCT Outcomes after angiography with sodium bicarbonate and acetylcysteine (PRESERVE) (2018) n=4,993. Composite 4.6 against 4.5 percent (OR 1.02, p=0.88). The contrast-nephropathy question is settled negative.
RCT Acetylcysteine for prevention of renal outcomes in patients undergoing angiography (ACT) (2011) n=2,308. Contrast-induced nephropathy identical at 12.7 percent in both arms.
RCT N-acetylcysteine, a glutamate modulator, in the treatment of trichotillomania (2009) n=50. 56 percent much or very much improved against 16 percent on placebo (p=0.003).
RCT N-acetylcysteine in the treatment of pediatric trichotillomania (2013) n=39. Null, with response 25 against 21 percent. The adult result did not carry into children.
Meta-analysis N-acetylcysteine in depressive symptoms and functionality: a meta-analysis (2016) 5 trials, n=574. Pooled SMD 0.37 (95% CI 0.19 to 0.55).
RCT Effects of N-acetylcysteine on semen parameters in idiopathic male infertility (2009) n=120 at 600 mg a day for 3 months. Improved volume, motility and viscosity with no change in concentration or morphology.
Observational The systemic availability of oral glutathione (1992) n=7. A single dose of about 3 g oral glutathione did not raise plasma glutathione, cysteine or glutamate over 270 minutes.
RCT Randomized controlled trial of oral glutathione supplementation on body stores of glutathione (2015) 6-month double-blind RCT, n=54. 1,000 mg a day raised glutathione stores 30 to 35 percent and more than doubled natural-killer cytotoxicity.
RCT Effects of oral glutathione supplementation on systemic oxidative stress biomarkers in human volunteers (2011) n=40 at 500 mg twice daily for 4 weeks. No significant change in oxidative-stress biomarkers (F2-isoprostanes p=0.38).
RCT Effects of N-acetylcysteine, oral glutathione and a novel sublingual form of glutathione on oxidative stress markers (2015) Crossover, n=20. Plain oral glutathione did not raise the reduced-to-oxidized ratio; the sublingual form did (p=0.002).
Observational Efficacy of glutathione for the treatment of nonalcoholic fatty liver disease (2017) Open-label pilot, n=34. Oral glutathione 300 mg a day for 4 months lowered ALT from 68.9 to 58.1 IU/L (p=0.014).
RCT Supplementing glycine and N-acetylcysteine (GlyNAC) in older adults improves glutathione deficiency and aging hallmarks (2023) 16-week RCT, n=24 older adults. The precursor combination corrected glutathione deficiency and improved oxidative stress and physical function.
Systematic review Systemic glutathione as a skin-whitening agent in adults (2020) Review of 3 RCTs. Glutathione was not beneficial enough as a skin-whitening agent and showed no long-lasting effect.
Label FDA Advisory No. 2019-182, unsafe use of glutathione as a skin lightening agent (2019) Regulatory warning. No approved injectable glutathione for skin lightening; risks include liver, kidney and nervous-system toxicity and Stevens-Johnson syndrome.

Glossary

Quick reference for the medical and technical terms used in this comparison.

NAC N-Acetylcysteine: The N-acetyl form of the amino acid cysteine. It supplies the rate-limiting building block the body needs to make glutathione, and it is the FDA-approved antidote for acetaminophen overdose.
GSH Reduced Glutathione: A three-amino-acid molecule (glutamate, cysteine, glycine) that acts as the cell's main internal antioxidant and powers Phase II detoxification.
GST Glutathione-S-Transferase: The enzyme family that attaches glutathione to toxins so the body can excrete them. This is the Phase II conjugation step people mean by detox.
ALT Alanine Aminotransferase: A liver enzyme measured on a standard blood panel. Honda 2017 tracked it as the endpoint in the glutathione fatty-liver pilot.
NK Natural Killer Cell: An immune cell that kills infected and abnormal cells without prior sensitization. Richie 2015 measured its cytotoxicity as the immune endpoint.
COPD Chronic Obstructive Pulmonary Disease: A progressive lung disease with airflow limitation and thick secretions. The setting for the PANTHEON and BRONCUS trials of NAC.
GlyNAC Glycine plus N-Acetylcysteine: A combination supplying two of the three amino acids in glutathione. Kumar 2023 tested it in 24 older adults over 16 weeks.
MADRS Montgomery-Asberg Depression Rating Scale: A clinician-rated depression score. Berk 2008 reported a mean difference of -8.05 on it for NAC in bipolar depression.

Nick Urban Health Optimization Researcher & CHEK Holistic Lifestyle Coach Level 2

I've spent over a decade testing supplements on myself and screening them for clients and podcast guests

Reviewed Sep 7, 2026 · next review Dec 6, 2026

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